There are numerous causes bears shimmy and scratch towards timber. Generally they convey by scent-marking timber, different instances they’re eradicating hair and scratching that hard-to-reach itch. A brand new examine posits a further perk: slathering on nature-made tick repellent.
When bears wriggle towards bark, the tree scratching posts leak out tars, resins and saps. The thick tar of beech timber sticks to fur and pores and skin the longest, and it’s waterproof, making it a powerful contender for an efficient tick repellent.
Agnieszka Sergiel, a bear biologist on the Polish Academy of Sciences and an creator of the examine printed final month within the Journal of Zoology, mentioned animals seldom interact in complicated behaviors reminiscent of rubbing towards timber for a single motive.
“We see loads of examples amongst mammals utilizing self-medication,” she mentioned. So, she and her colleagues determined to check whether or not rubbing towards timber may shield bears towards parasites.
For years, biologists have noticed that brown and black bears have an affinity for sure sorts of timber — particularly beech timber. The timber’ enchantment is so robust that scientists use the sticky, robust scents of beech tar to draw bears for research or to name them inside in zoos.
To check the speculation that beech tar is a tick repellent, Dr. Sergiel discovered herself looking at tube after tube of tar and trapped Dermacentor reticulatus, a widespread onerous tick recognized to feast on bears. She watched to see if the ticks would run away from beech tar on one facet and towards protected, plain water on the different finish of the tube.
And run they did!
“It was actually apparent they hated the beech tar,” mentioned Agnes Blaise, a biologist on the College of Strasbourg in France and an creator of the examine. “Some had been actually speedy, operating round and hiding beneath the water.”
The researchers additionally examined turpentine, a bear attractor, and the ticks despised it as nicely.
The one ticks that didn’t rely, Dr. Sergiel added, had been those that managed to flee the tube totally.
“There have been some Houdinis,” she mentioned, “however they had been good lab animals.”
The researchers targeted on ticks for his or her examine as a result of they’re geographically widespread and environmentally versatile — and due to local weather change, spreading farther and remaining energetic longer. Ticks are additionally illness vectors, though scientists are nonetheless studying about what pathogens they unfold to bears.
The straightforward results of beech tar not being common with ticks gives the primary experimental proof supporting the longstanding concept that tree resins may act as a bug repellent.
The researchers “had a pleasant, tidy experiment that supplied some fairly clear proof” that ticks had been avoiding beech tar, mentioned Andrea Morehouse, an impartial wildlife biologist in Alberta whose work focuses on bear-human interactions and was not concerned within the examine. “Repelling parasites might be not the first perform of tree rubbing, nevertheless it actually could possibly be a further profit.”
Hannah Tiffin, an entomologist whose graduate analysis at Penn State College targeted on ticks and bears, hadn’t heard of the concept of tree tar as insect repellent.
“I believe it’s a extremely fascinating path to go and will make sense,” she mentioned.
Different animals within the wild use nature-provided bug repellents; for instance, Capuchin monkeys studiously rub their fur with citrus and dolphins could deal with their pores and skin with coral. Your cat could even use catnip as a mosquito repellent. So it’s completely believable that bears may accomplish that, too, mentioned Dr. Tiffin, who was not concerned within the examine and is now a postdoctoral researcher on the U.S. Division of Agriculture.
There’s nonetheless so much to be discovered about tar as a tick repellent, Dr. Sergiel famous. Constructing out the scarce information of parasites discovered on bears within the wild (together with ticks) can be probably the most vital steps to furthering this work, the researchers mentioned. Amassing fur and resin samples from bears and testing parasites’ responses to these supplies is also helpful, Dr. Tiffin added.